Protective electric switch-box.



No. 733,560. PATENTED JULY 14, 1903.

' A. SUNDH. PROTECTIVE ELECTRIC SWITCH BOX.

APPLICATION FILED FEB. 20, 1901.

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WITNESSES:

I PATENTED JULY 14,1903.

A. SUNDH. PROTECTIVE ELECTRIC SWITCH BOX.

APPLICATION FILED FEB. 20, 1901.

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PATENTED JULY 14 A. SUNDH. PROTECTIVE ELECTRIC SWITCH BOX.

APPLICATION FILED ran. 20. 1901.

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WITNESSES:

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PATENTED JULY 14, 1903.

A. SUNDH. PROTECTIVE ELECTRIC SWITCH BOX.

APPLICATION FILED FEB. 20, 1901.

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No. 733,560. PATENTED JULY 14, 1903. A. SUNDHL PROTEGTIVHELEGTRIG SWITCH BOX.

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PATENT OFFICE.

AUGUST SUNDH, OF YONK ERS, NEW YORK.

PROTECTIVE ELECTRIC SWITCH-BOX.

SPECIFICATION forming part of Letters Patent No. 733,560, dated July 14:, 1903. Application filed February 20, 1901. Serial No. 48,123. (No model-l To all whom it may concern:

Be it known that 1, AUGUST SUNDH, of Yonkers, county of VVestchester, State of New York, have invented a new and useful Improvement in Protective Electric Switch- Boxes, of which the following is a specification.

This invention relates, broadly, to the incorporation into an electric conduit of a transversely enlarged section in the form of a switch-box provided on the bottom with a plurality of pairs of stationary contacts, the members of each pair of which are insulated from each other, but are electrically connected with opposite terminals of line-wires carried in the conduit, and also provided with a removable cover carrying a corresponding plurality of bridges, each composed of a pair of contacts insulated from the cover, but electrically connected with each other by a strip of fusible metal. When the cover is closed, the contacts of the bridges engage the stationary contacts, and thereby establish the electrical connection with each other of the opposite terminals of the several line-wires. It thus results that the electric circuit or circuits extending through the conduit become closed by the closing of the cover and opened by the removal of the cover. As the switchbox needs no support other than that which it derives from its mechanical connection with and incorporation into theconduit, the advantage accrues that the switch-box may be located in any part of the conduit which may be most convenient.

The invention embraces a variety of improvements in the construction of the switchbox which are susceptible of useful employment either singly or collectively, as pointed out in the course of the subjoined description of the apparatus in detail.

The accompanying drawings, illustrating a switch-box containing the present improvements, are as follows:

Figure 1 is a side elevation. Fig. 2 is a top view with the cover removed. Fig. 3 is a longitudinal vertical section taken through the plane indicated by the dotted line 00 on Fig. 2. Fig. 4 is a front end elevation. Fig. 5 is Fig. 6 is a top View of a switch-box with the coverremoved, illustrating a modification adapting the invention for employment in connection with a three-wire system and also illustrating the connection of the switch-box with the multiplicity of conduitpipes each containing a single conductingwire.

The apparatus shown in the drawings consists of a switch-box A, provided at its ends with screw-threaded bosses A and A into which are screwed, respectively, the opposed screw-threaded ends B B of the metallic pipes G O, forming parts of the electric conduit for containing the insulated wires of the desired plurality of circuits. By such screw-threaded or other suitable connections the switch-box is made to become a fixed section of the conduit.

It may possibly be desired to detach the switch-box without disturbing the pipes C C. In the example of means for effecting this purpose herein shown the body of the box is constructed of two parts ct b, separable from each other upon the plane o o, coinciding with the plane of the central longitudinal axes of the bosses A A and the conduit-pipes O C. The lower part a of the body of the box is provided on each side with the horizontally-projecting vertically-perforated ears a a and the upper part b with corresponding vertically-perforated ears I) b for engagement by the clam ping bolts and nuts 19 11 by the application ofwhich the parts a and b of the box are securely clamped together. The removal of the said clamping-bolts permits the parts a and b of the body of the switchbox to be laterally detached from and replaced in the conduit Without rotating the pipes C C. It will also be observed that the part b of the box is flanged at its sides to receive the part a and that the said flanges close and protect the junction.

The expedient of constructing the switchbox of separable parts is in itself useful, but need not necessarily be employed. If not employed, the part b of the body of the box may be integral with the part a. In any case the cover D is connected by the hinge D with the end of the partb immediately above the boss A. In the opposite end of the cover is pivoted a vertical lever d, the downwardlyextending arm of which is provided with a hook d, adapted to hold the cover closed by catching under the lug d projecting outwardly from the wall I) immediately above the boss A The lever d has a laterally-projecting arm d which is constantly subjected to the upward thrust of the spring d", affixed to the top of the cover. The upwardly-extending arm (1 constitutes the trigger for so rocking the lever d upon its pivot as to disengage the hook d from the lug d, and thus permit the cover D to be raised.

The raising of the cover'D is effected by raising the lifter-arm E, which is provided with the handle E and which is pivotally connected at one end with the hinge D and near its opposite end is provided with the vertical aperture E for admitting and-actuating the trigger-arm (Z As the lifter-arm rises the trigger-arm d is so rocked by its engagement with the wall of the aperture E as to ultimately disengage the hook d from the lug d The lifter-arm E has fastened to its under side a stout spring 6, suitably connected to the cover D, so that it is subjected to increasing tension as the lifter-arm rises,whereby as soon as the hook cl is disengaged from the lug (Z the force of the thus-charged spring 6 tends to throw the coverD quickly upward, and thus separate the contacts within the switch-box with the snap action which is so desirable in opening electric circuits. Provision is made for starting the upward movement of the cover D, if necessary, by the direct action of the lifter-arm. For this purpose the hinged end of the lifter-arm is provided with the shoulder 6, adapted to engage a preferably adjustable stop-bolt c inserted through a part of the hinge D which is connected with the cover D, so that in case the cover sticks it will by the direct action of the lifter-arm be started, and thus freed to the action of the charged spring 9.

To guard against the unauthorized opening of the switch-box, a lock-as, for example, the lock Fis provided for locking the lifter-arm E to the trigger-arm (1 which is slotted to admit the bail of the padlock F.

Adjacent the lifter-arm E, on each side, are the manually-operable wing-nuts G G, engaging the screws 9 g, inserted through the countersunk aperture g g in the insulating contact-holding plate H and extending upwardly therefrom through the cover D, as illustrated in Fig. 3, so that if occasion require the cover D may be lifted clear of the plate H. The countersinks g arepreferably contracted on their mouths, and are thus adapted to securely retain any suitable sealing material g, by which the screws g g are held in place in the plate H. The positive and negative service-wires I t extend from the conduit-pipe 0 through the rear end I of the switch-box and are electrically connected with the fork-contacts 1%, respectively. The positive and negative distributing-wires I 2' extend from the conduit-pipe 0 through the front end j of the switch-box and are electrically connected with the fork-contacts I 2' respectively. All the said fork-contacts are secured to the plate L of insulating material, such as slate, which is fastened to the bottom of the switch-box. The inner surface of the wall of the switch-box is lined with tarred paper or other suitable insulating material, and midway between the pairs of fork-contacts there is placed the longitudinal vertical protective partition M,usually of slate,which extends upward from the bottom plate L nearly to the position occupied by the under side of the insulating-plate H when the cover D is closed. The purpose of this construction is to guard against the formation of an are between adjacent fork-contacts of opposite polarities. Electrical connectionbetween the fork-contacts 1 and I and between the fork-contacts 2" and t is established when the cover D is closed by the engagements with the said fork-contacts, respectively, of the movable knife-contacts 1 and I and i and i, which are fastened to the insulating-plate H. The knife-contacts I and I are electrically connected with each other by the fusible strip I ,and similarly the knife-contacts 'Fand are electrically connected with each otherby thefusiblestripi An advantageofthisconstruction is that when the cover D and theinsulating-plate H fastened thereto are raised both bridges, consisting, respectively, of the knife-contacts 1 1 with their fusible connecting-strip I and the knife-contacts i 1', with their fusible connecting-strip 71 are Wholly separated from the live wires, so that, if required, a burned-out fusible strip can be replaced without danger of a shock from aliv wire.

The switch-box may of course be increased in width and provided with as many pairs of contacts as may be desired. For example, the switch-box may be adapted for the threewire system by providing a third pair of forkcontacts N 'n, as shown in Fig. 6, in which case an additionalpair of knife-contacts will be appropriately affixed to the insulatingplate H and an additional longitudinal protective partition M will be employed.

From the foregoing description it will be perceived that my improved construction will subserve the purposes of a switch and a fuseblock, that it may be placed wherever it is most convenient without requiring any material modification of the path of the conduit, that all parts intended to be used as conductors are completely shielded and protected, that there is no danger of short-circuiting, that it may be easily operated and safely repaired if a fusible strip burns out, and that there is no danger of fire from the molten metal of a burned-out fuse.

It will of course be understood that the described switch-box is susceptible of useful employment even if for any reason the fusible strips are omitted and the contacts of each bridge are connected with each other by infusible metal.

What is claimed as the invention is 1. A protective switch-box provided with a removable cover carrying a plurality of bridges composed of pairs of suitably-insulated contacts connected by fusible strips and provided with a corresponding plurality of suitably-insulated contacts appropriately connected with the service and distributing wires and directly secured to and thereby forming an enlarged section of an electric conduit containing said wires.

2. In combination with an electric conduit, a protective switch-box supported by said conduit provided with a removable cover carrying a plurality of bridges, each composed of a pair of suitably-insulated contacts connected by a fusible strip, and provided with a corresponding plurality of pairs of suitably-insulated stationary contacts appropriately connected to the terminals of corresponding pluralities of wires extending respectively into different parts of said box, whereby the appropriate electrical con nection with one another of the said pluralities of wires is established by closing said cover and disestablished by opening said cover.

3. In combination with an electric conduit, a protective switch-box supported by said conduit containing a plurality of pairs of insulated stationary contacts appropriately connected to the service and distributing wires, a vertical partition composed of insulating material erected between and extending higher than said stationary contacts for the purpose of opposing the formation of any are between adjacent stationary contacts of relatively opposite polarities.

4. In a protective switch-box provided with a removable cover for carrying pairs of contacts appropriately secured to an insulatingplate; fastening devices for holding said plate to said cover and means for unfastening said devices manually operative from the exterior when said cover is closed.

5. AprotectivesWitch-box bodyhavingtwo parts separable upon a plane coinciding with the central longitudinal plane of the axes of the conduit-pipes inserted in the said box, and removable clamping devices for normally clamping said two parts together; in combination with a cover hinged to one of said parts and circuit-closing means carried on the inside of said cover.

6. In a protective switch-box, a hinged cover provided with a latch for holding said cover closed and thereby keeping closed an electric circuit within said box; a hinged lifterarm having a prescribed limited range of independent swinging movement in the plane of movement of said hinged cover and adapted to release said latch during said range of independent movement, in combination with a spring connecting said lifter-arm with said cover, whereby the resilient force stored up in said spring by said independent movement of said lifter-arm tends, when said latch is released, to quickly open said cover and break said circuit with a snap action.

7. In a protective switch box, a hinged cover provided with a latch for holding said cover closed and thereby keeping closed an electric circuit within said box; a lifter-arm hinged to said cover and adapted when lifted to release said latch; a spring connecting said lifter-arm with said cover and a stop connected with said cover for limiting the switching movement of said lifter-arm, independ ently of said cover, to a range sufficient to enable it to release said latch and for receiving and positively communicating to said cover the direct action of the said lifter-arm.

8. In an electric switch-box substantially of the character described, a hinged cover; a latch for holding said cover closed; a litterarm hinged to said cover and adapted to control said latch and a lock for locking said lifterarm to said cover.

9. In an electric conduit, an enlarged portion composed of three sections, means for clamping two of said sections together forsecuring them to other parts of said conduit,

means for pivotally securing the third section to one of the other sections and circuitclosing means carried within said pivotallysecured section.

10. The combination with a conductor and its conduit-pipe, of a protective switch-box having a section containing terminal contactpieces connected to said conductor and provided with a semitubular extension at each end, a frame forming an intermediate section of said box and provided with semitubular extensions to meet said extensions of said first-named section to form tubes adapted to receive said conduit-pipes, means for detachably securing said sections together, and'a cover-section secured on said intermediate sec tion and provided with circuit-closing plates on its innerside adapted to cooperate with said contact-terminals.

AUGUST SUNDH. \Vitnesses:

A. M. J ONES, E. GATTERER. 

